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NuVinci continuously variable transmission
Nuvinci Cycling technology currently under development for other applications, including wind turbines, light electric vehicles, outdoor power equipment, and automotive front-end accessory drives.[citation needed]
Mechanical variators existed since the 1800s, and have been used successfully in machinery, particularly the Kopp tilting ball variator. Various attempts have been made to implement them in vehicle transmissions, but commercial success has been elusive.
In 2017 it was announced that NuVinci Cycling would be renamed as Enviolo. In February 2018, the company filed for Chapter 11 bankruptcy. In June 2018, the company emerged from restructuring under Chapter 11 bankruptcy, and under new ownership the bike division was rebranded as Enviolo.
The NuVinci CVT gear system uses a set of rotating and tilting balls positioned between the input and output discs of a transmission. Tilting the balls changes their contact diameters and varies the speed ratio. As a result, the NuVinci CVT system offers seamless and continuous transition to any ratio within its range. The gear ratio is shifted by tilting the axles of the spheres in a continuous fashion, to provide different contact radii, which in turn drive input and output discs. The system has multiple "planets" to transfer torque through multiple fluid patches. The spheres are placed in a circular array around a central idler (the sun) and contact separate input and output traction discs. This configuration allows input and output to be concentric and compact. The result is the ability to sweep the transmission through the entire ratio range smoothly, while in motion, under load, or stopped.
Two factors allow the NuVinci CVT to provide a continuously variable ratio range in a compact package:
The NuVinci CVT system has a small number of parts. Most CVTs have lower mechanical efficiency than competitive conventional transmissions.
Since any CVT may allow a power plant, human or motorized, to operate at (or closer to) its speed of optimal efficiency, output torque or output power, the NuVinci CVT may improve a system's overall efficiency or performance compared to a 'conventional' geared transmission, but only if such gain in the efficiency or performance of the power plant exceeds any loss in efficiency or performance that may be introduced by replacing the conventional transmission with the NuVinci CVT. For example, if the NuVinci CVT were only 90% as efficient as the conventional transmission it replaced, the gain in operating efficiency from the power plant would have to be 11% (i.e., 1/0.90 − 1 = 0.11 or 11%) before the overall efficiency improved. The company does not provide any numbers relating to efficiency of their transmissions, and has declined to do so when requested.
The NuVinci CVT further offers the ability to accept multiple inputs while varying speed and ratio, managing torque and providing single or multiple power outlets. By supporting a torque-demand rather than a speed-demand control solution, the NuVinci CVT solves the low-speed acceleration problem inherent in some torque-demand vehicles.
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NuVinci continuously variable transmission AI simulator
(@NuVinci continuously variable transmission_simulator)
NuVinci continuously variable transmission
Nuvinci Cycling technology currently under development for other applications, including wind turbines, light electric vehicles, outdoor power equipment, and automotive front-end accessory drives.[citation needed]
Mechanical variators existed since the 1800s, and have been used successfully in machinery, particularly the Kopp tilting ball variator. Various attempts have been made to implement them in vehicle transmissions, but commercial success has been elusive.
In 2017 it was announced that NuVinci Cycling would be renamed as Enviolo. In February 2018, the company filed for Chapter 11 bankruptcy. In June 2018, the company emerged from restructuring under Chapter 11 bankruptcy, and under new ownership the bike division was rebranded as Enviolo.
The NuVinci CVT gear system uses a set of rotating and tilting balls positioned between the input and output discs of a transmission. Tilting the balls changes their contact diameters and varies the speed ratio. As a result, the NuVinci CVT system offers seamless and continuous transition to any ratio within its range. The gear ratio is shifted by tilting the axles of the spheres in a continuous fashion, to provide different contact radii, which in turn drive input and output discs. The system has multiple "planets" to transfer torque through multiple fluid patches. The spheres are placed in a circular array around a central idler (the sun) and contact separate input and output traction discs. This configuration allows input and output to be concentric and compact. The result is the ability to sweep the transmission through the entire ratio range smoothly, while in motion, under load, or stopped.
Two factors allow the NuVinci CVT to provide a continuously variable ratio range in a compact package:
The NuVinci CVT system has a small number of parts. Most CVTs have lower mechanical efficiency than competitive conventional transmissions.
Since any CVT may allow a power plant, human or motorized, to operate at (or closer to) its speed of optimal efficiency, output torque or output power, the NuVinci CVT may improve a system's overall efficiency or performance compared to a 'conventional' geared transmission, but only if such gain in the efficiency or performance of the power plant exceeds any loss in efficiency or performance that may be introduced by replacing the conventional transmission with the NuVinci CVT. For example, if the NuVinci CVT were only 90% as efficient as the conventional transmission it replaced, the gain in operating efficiency from the power plant would have to be 11% (i.e., 1/0.90 − 1 = 0.11 or 11%) before the overall efficiency improved. The company does not provide any numbers relating to efficiency of their transmissions, and has declined to do so when requested.
The NuVinci CVT further offers the ability to accept multiple inputs while varying speed and ratio, managing torque and providing single or multiple power outlets. By supporting a torque-demand rather than a speed-demand control solution, the NuVinci CVT solves the low-speed acceleration problem inherent in some torque-demand vehicles.